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Here is lovely 1975 Centurion Semi Pro. It has been well preserved over the decades by its original owner, and I am now the proud steward of this extraordinary machine.

As readers of this blog already know, I have been on a decades long quest to replace my crashed 1976 Centurion Pro Tour, a bike which was my only bike for over 20 years, and upon which I logged over 40,000 miles including tours of the Pacific Northwest, the San Juan Islands, and Canada, as well as serving as my daily commuter. The Pro Tour was my original all-rounder.

So, when I saw this baby blue 1975 Centurion Semi Pro on eBay, I knew I would be honored to shepherd this bike into its next phase.

When the bike arrived, I unpacked it like a toddler with a new toy, and when I found these interesting frame transfers, they confirmed the information provided by the seller of the bike (who was not the original owner, but who sold it on their behalf). The first human to ride this Centurion was a member of the US Cycling Federation (now known as USA Cycling), and had ordered the full Dura Ace upgrade for this bike, as well installing racing tubulars instead of the 27″ clincher rims offered as standard equipment. The original owner was also a member of the League of American Wheelmen and had added these black and white racing flag transfers to the top tube.

While the bike clearly had a documented racing heritage, I was puzzled to find the Dura Ace crankset mounted with a chainguard. And, you’ll note that the rings are not in racing configuration, but are a compact set-up with 52 teeth on the large ring and 39 on the small ring. Both rings are Shimano Dura Ace. Don’t forget to notice the lovely Dura Ace front derailleur. The Dura Ace upgrade included: the front derailleur, the anodized brake calipers, the drilled levers and the crankset:

These Dura Ace components are in amazing condition. The drilled levers look new, but are given away by the gum hoods which have long ago lost their resilience. The brake calipers are beautifully anodized. The Dura Ace crankset with its 172.5 arms is in equally amazing condition, considering its 43 years in service.

I enjoyed seeing this unusual Huret wrap around chrome cable guide which provides shifter cable routing on both sides of the frame. This bike has zero braze-ons. While it is built with Tange Prestige #1 tubing, during this era braze-ones were rare, and most needed accessories and cable guides were handled via clamps.

SunTour Mighty ratcheting downtube shifters

Shimano Crane GS drilled long cage derailleur

SunTour GS chromed dropouts with single eyelet and adjuster screws

The drivetrain consists of SunTour ratcheting Mighty shifters mated to the Dura Ace front derailleur and a Shimano Crane GS rear derailleur. The Crane would be needed to handle the 52/39 rings up front. The dropouts are by SunTour, and I don’t think I’ve ever seen anything as lovely as these fully chromed SunTour GS dropouts. Their unusual shape made me look up this component in the SunTour catalog. You’ll note that the design pushes the dropouts inward toward the hub. I wonder if this simplified mitering the rear stays.

The pedals also provided a surprise – they are very rare Barelli Supreme pedals, with the optional alloy cages. According to the site Classic Lightweights, these pedals “were considered the Rolls Royce of pedals. The spindle was made from Nickel Chrome Steel and they were machined for accuracy at the bearing surfaces and they came with a life time guarantee” That, and the other component upgrades help to explain why this bike weighs in at 22 lbs.

The upgraded wheelset consists of 27″ Super Champion Competition tubular rims laced to Sunshine Pro Am low flange hubs. A new set of Pararacer 20mm tubulars were installed as part of the deal. I’m not sure how well the new tubulars were glued, so I will probably install a clincher wheelset on hand for this bike’s first test ride.

The bars were upgraded to 3TTT, mated to a Cinelli stem. The original SR seatpost looks beautiful with this Cinelli leather Unicantor saddle. Unicantors were the first plastic base saddles of this era. I haven’t ridden one before and look forward to trying it out. You’ll also note the Centurion’s impressive, chrome wrap around seat stay.

This Semi Pro has the following SN: M5J00027. Consistent with all Centurion frames I have encountered, and as documented by others, the first letter indicates the frame builder, but no one knows who that is. Since both my 1976 Pro Tour and this 1975 Semi Pro start with an “M” I will guess they were both built by the same manufacturer, probably Japanese. The second numeral is a “5” and that indicates the year built – 1975 – which is consistent with the bike’s components. Another way to date a bike without a reliable serial number is by the components.

Some readers might wonder about the photos in this post. For the most part I used my Panasonic Lumix mirrorless camera, but I also brought out my Leica Digilux 2 for some of the photos seen here.

I look forward to venturing out on this extraordinary bike, and will keep you posted on our progress.

Rear dropouts determine what derailleur options are available for a given frame. Rear dropout spacing also determines hub options, with derailleur equipped vintage bicycles having narrower spacing than their modern counterparts. And, the shape and style of the dropout are important as well: horizontal dropouts allow for wheel adjustment fore and aft, whereas vertical dropouts make rear wheel removal easier. Eyelets on the dropouts mean integrated fender and rack mounts, a definite plus.

Plain dropouts require a “claw” attachment for the rear derailleur or a braze-on or clamp for the chain stay. For vintage bicycles, plain dropouts without a hanger do not in any way indicate a lower end frame. Many nice upper end vintage steel frames did not have manufacturer specific brazed dropouts. So, do not be afraid of the “claw”. In fact, having plain dropouts on a vintage bicycle can be helpful, because derailleur options are automatically expanded, depending on the style of claw chosen.

The above Daniel Rebour drawings depict two different styles of Huret dropouts. Huret rear derailleurs can be a bit (translate “a lot”!) more difficult to set up than Simplex derailleurs. By contrast, setting up Shimano, Suntour or Campagnolo derailleurs with their matching tabbed and threaded dropout at 7 o’clock seems almost too easy.

1972 Mercian Shimano dropout

After the early 1980’s or so, dropout hangers were not so much an issue, because dropouts on derailleur equipped bikes after this point in time featured standard Shimano/Campagnolo hangers which were adopted as the standard by other component manufacturers.

Sheldon Brown’s dropout chart

Sheldon Brown developed this helpful chart shown above, although it is missing some key information. He does not address the baffling array of hanger styles which existed in days of yore.

A Simplex early style dropout with tab on the non drive side.

Hangerless dropout, requiring a claw

Campagnolo semi-horizontal dropouts on a 1970’s Jack Taylor

Stamped plain dropouts on an early 1970’s Raleigh with a 531 frame

There is only one resource on the web that seems to have a comprehensive overview of dropout styles and rear derailleur compatibility issues. This helpful chart can be found at a site called The Headbadge. Velobase also has an extensive database of vintage style dropouts. These resources can help anyone restoring a vintage bicycle determine whether and how to change the existing rear derailleur, and how to determine compatibility options.

In addition, there are a few other web resources that can help you with derailleur and dropout considerations:

The Dancing Chain by Frank Berto is also an important resource – even more so because it is in book form. If you don’t want to explore vintage derailleurs and dropout styles, the information presented in Chapter 15 – “How Derailleurs Work” will be worth the cost of purchasing this book. The author’s discussion of derailleur composition, chain gap, pulley spacing, cage geometry, and spring loaded pivots is invaluable to an understanding of how derailleurs work.

Of all the fads and trends in the cycling industry, the touring era that accompanied the 1976 BikeCentennial in the U.S. was probably the most positive. While not everyone wants or needs a touring bike – a touring bike is a bike that can work well for all kinds of riding. And, due to economic conditions during this era – favorable exchange rates for the Japanese yen and the oil crisis of the early 70’s – the U.S. market was flooded with low cost, high quality touring bikes in the mid 70’s to mid 80’s. These bikes often survive intact, as they were quite well made to begin with, and were usually equipped with top of the line components.

Japanese brands like Centurion, Nishiki, Bridgestone, Fuji, Miyata, Panasonic, and Univega were among the most well known manufacturers to build high quality touring bicycles. Raleigh, Peugeot, Trek, Specialized, Austro-Daimler, Gitane, Motobecane, Mercier, and others also joined in to build some of the nicest touring bikes ever mass produced.

These touring bikes of the late 70’s and early 80’s hold a special place in my heart. Their excellent build quality and beautiful design represent freedom, exploration, and adventure.

This lovely 1985 Nashbar Toure MT is a great example of the quality that could be had for a reasonable price. The frame was built for Nashbar by Maruishi – a Japanese builder not as well known as others, but still producing a beautifully brazed machine of double butted cro-mo steel. The gorgeous blue sparkle paint and well brazed seat cluster show off its quality.

All the finish work is top notch. This is a bike I would keep for myself if it were my size.

Seat tube has no bottle cage braze-ons – left clean for mounting a frame pump.

There are so many nice features on this amazing bike that it’s hard to list them all. One reason that the bike is so pristine, however, is because long ago the SunTour Mountech rear derailleur had failed, and the bike was put away, thankfully in a dry, clean space.

So, I replaced the rear derailleur with a Shimano 600 long cage mechanism from the same era. It works perfectly with the original 100% SunTour drivetrain.

Triple crank with half step gearing.

This bike was built in the days of gear shifting pattern obsession. Half step gearing was a way to have a routine shifting pattern that would maintain cadence as the terrain changed. In practice, at least for me, I prefer not having to constantly double shift, so I am not enamored with half step gearing and have, when confronted with it, replaced the large middle chain ring with something smaller, such as a 40 or 42. But, some riders love half-step gearing and more power to them (pun intended).

It would be tough to find a similarly engineered touring bike with these quality components, for a price that even remotely comes close to what you can buy this bike for now. One problem is that most cyclists associate Nashbar with low end liquidation components, rather than any kind of quality. But, back in the 1980’s, the arrival of the Nashbar mail order catalog was an exciting event. I ordered many wonderful and interesting components for my old 1976 Centurion from Nashbar back then. Today, however, the company is known for its discounted and discontinued parts, rather than for quality bicycles, for better or for worse.

This wonderful old touring machine is going to a friend’s stable in Southern Oregon, where I know it will be ridden and appreciated. I hope to join him and his spouse on some wonderful rides through Southern Oregon wine country, and I will be a bit jealous his bike.